The "let's brainstorm how to make a piggyback work" thread

[eTiMaGo]

OK guys, as most of you know, getting a piggyback to work on a USDM yaris has been a major PITA for those who have tried.

That being said, we seem to be (at least I am) a bit in the dark as to why and how that is.

So I propose we use this thread to discuss what has been tried, what hurdles have been met with, and how we could do this.

Let's remember the Yaris is not some magical device conjured out of the mind of a madman... It is a human construction based on human-devised electronic systems, and thus these systems can be reverse-engineered by other humans

I, unfortunately, have no experience in this outside of the theoretical, but I've been reading the technical/repair manuals in quite a lot of detail and have a good understanding of the various quirks of this car, especially with regards to its emissions systems... so let the discussion begin!

[jinxor]

Sorry for being a n00b... but can you explain what a piggyback is as well at the beginning of the thread please

[tk-421]

Originally Posted by jinxor

Sorry for being a n00b... but can you explain what a piggyback is as well at the beginning of the thread please

Google is your friend:
http://www.innovatemotorsports.com/r...piggy-back.php
http://forums.superstreetonline.com/...eng/index.html

[Sabretooth]

Honestly, had you thought about getting a USDM unit Thomas and trying to take it to TRD Thailand? See what they can come up with, they seemed to help you in the past about trying to sort out what Engine swaps were viable in the past.

We dont have those kind of tuning places here in the states, or at least a mainstream company that can sit there and devote time and money to try and reverse engineer it for us.

[yaris-me]

I think Toyota has engineered the car to be reliable and has built in a margin of safety for the engine. On the surface, the engine seems to have been designed for performance yet it is detuned by a margin of safety. So, I think the problem is in the ECU programming and not a piggyback. Finding a way to alter or change the programming is the way.

[jkuchta]

Reading through the Engine management section of the factory manual, there seems to be a route to add/subtract fuel and spark with an intelligent tester plugged into the OBD-II port. There is a way to also turn off the DFCO and a bunch of other things.


Anyone have access to an intelligent tester?

[dallas]

The problem is not the cars complex unbreakable programs, it's the lack of tuners and enthusiasts who are willing to figure this out, that leaves us newbies on the forums to figure it out on our own. Even the suppliers don't want to waste any money to offer a real turn key kit, they want us to figure it out and be their North American guinea pigs. That being said, NT Nooge, and several other guys that have the Blitz supercharger that are working hard to get the most out of this kit, and get the tuning dialed in. Sadly this is a Econo car not a Sports car.

Its funny I was just on a Genesis Coupe form and because its a 2.0 turbo, it's not much faster stock than a Yaris 0-60 in 8 seconds, Hyundai has done a great job to make it tuner friendly, they hooked up with companies like AEM and AMS to make stuff for the car, I bet in no time this platform will be over 300 hp. And at $22,000 a rear wheel drive with 200 hp, big Brembo brakes that looks like a G37 Nissan is very attrative right now.
I hope we can figure out a safe reliable way to get an honest 130 at the wheels of out the Yaris, the lack of Hp has my eyes wandering LOL

[Nexus1155]

^^^ yeah but you have to take into account that the genesis weighs 3500lbs when the yaris weighs around 2000. Thats a 1500 lb difference, i think you would be as fast as the yaris is you weighed that much...

[eTiMaGo]

Originally Posted by Sabretooth

Honestly, had you thought about getting a USDM unit Thomas and trying to take it to TRD Thailand? See what they can come up with, they seemed to help you in the past about trying to sort out what Engine swaps were viable in the past.

We dont have those kind of tuning places here in the states, or at least a mainstream company that can sit there and devote time and money to try and reverse engineer it for us.

That is definitely an option, can anyone get their hands on an ECU from a salvaged car? I checked some time ago with ROCKLAND TOYOTA, the part numbers are completely different between our ECUs here and the USDM ones.

Originally Posted by PK198105

i believe the major hurdle is the ECU, its just too well protected and is not add-on friendly. what would need to be done is a interface between the ECU and the piggyback, not to "fool" the ECU but merely reroute its responses.

One of the main problem, I think, which prevents simple piggybacks like the S-AFC which modify the MAF signal, is that the ECU uses data from the AF and O2 to check on the final air/fuel ratio, and override whatever data it is getting from the MAF (fuel trim function)

Originally Posted by yaris-me

I think Toyota has engineered the car to be reliable and has built in a margin of safety for the engine. On the surface, the engine seems to have been designed for performance yet it is detuned by a margin of safety. So, I think the problem is in the ECU programming and not a piggyback. Finding a way to alter or change the programming is the way.

Yes, an ECU tweak is usually the fastest, cheapest and most warranty-friendly way to do this. But nobody yet seems to know how to do that, and it would require some pretty advanced electronics knowledge and experience, beyond the scope of this discussion.

Originally Posted by jkuchta

Reading through the Engine management section of the factory manual, there seems to be a route to add/subtract fuel and spark with an intelligent tester plugged into the OBD-II port. There is a way to also turn off the DFCO and a bunch of other things.


Anyone have access to an intelligent tester?

I think that is only for diagnostic purposes, once you return the car to normal usage it will re-adjust itself.

I checked eBay for those intelligent testers, $2000+

Originally Posted by dallas

The problem is not the cars complex unbreakable programs, it's the lack of tuners and enthusiasts who are willing to figure this out, that leaves us newbies on the forums to figure it out on our own. Even the suppliers don't want to waste any money to offer a real turn key kit, they want us to figure it out and be their North American guinea pigs. That being said, NT Nooge, and several other guys that have the Blitz supercharger that are working hard to get the most out of this kit, and get the tuning dialed in. Sadly this is a Econo car not a Sports car.

Sad but true, unfortunately. Same reason Holdener seems to have given up on the intake manifold, it'll never sell enough to be worth the trouble. But hey, we are owners and fans of the cars, we're (mostly) not stupid, we can figure this out together somehow!

Its funny I was just on a Genesis Coupe form and because its a 2.0 turbo, it's not much faster stock than a Yaris 0-60 in 8 seconds, Hyundai has done a great job to make it tuner friendly, they hooked up with companies like AEM and AMS to make stuff for the car, I bet in no time this platform will be over 300 hp. And at $22,000 a rear wheel drive with 200 hp, big Brembo brakes that looks like a G37 Nissan is very attrative right now.
I hope we can figure out a safe reliable way to get an honest 130 at the wheels of out the Yaris, the lack of Hp has my eyes wandering LOL

Yeah that Genesis coupe is gonna make some big waves in the future of import tuning in the US, beating Nissan and Toyota at their own game... But let's stay on topic

[eTiMaGo]

Just gonna note down a few ideas here for reference...

Repair manual description of operation of the various sensors:

Mass Air Flow:

The MAF meter is a sensor that measures the amount of air flowing through the throttle valve. The ECM
uses this information to determine the fuel injection time and to provide an appropriate air-fuel ratio. Inside
the MAF meter, there is a heated platinum wire which is exposed to the flow of intake air. By applying a
specific electrical current to the wire, the ECM heats it to a specific temperature. The flow of incoming air
cools both the wire and an internal thermistor, affecting their resistance. To maintain a constant current
value, the ECM varies the voltage applied to these components of the MAF meter. The voltage level is
proportional to the airflow through the sensor, and the ECM uses it to calculate the intake air volume.
The ECM monitors the average engine load value ratio to check the MAF meter for malfunctions. The
average engine load value ratio is obtained by comparing the average engine load calculated from the
MAF meter output to the average engine load estimated from the driving conditions, such as the engine
speed and the throttle opening angle. If the average engine load value ratio is below the threshold value,
the ECM determines that the intake air volume is low, and if the average engine load value ratio is above
the threshold value, the ECM determines that the intake air volume is high.
If this is detected in 2 consecutive driving cycles, the MIL is illuminated and a DTC is set.

Intake Air Temperature sensor:

The Intake Air Temperature (IAT) sensor, mounted on the Mass Air Flow (MAF) meter, monitors the IAT.
The IAT sensor has a built in thermistor with a resistance that varies according to the temperature of the
intake air. When the IAT is low, the resistance of the thermistor increases. When the temperature is high,
the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes (see
Fig. 1).
The IAT sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R.
Resistor R and the IAT sensor are connected in series. When the resistance value of the IAT sensor
changes, according to changes in the IAT, the voltage at terminal THA also varies. Based on this signal,
the ECM increases the fuel injection volume when the engine is cold to improve driveability.

(Both MAF and IAT sensors are located in the plastic "plug" that goes into your intake)

Front A/F sensor:

The A/F sensor generates a voltage* that corresponds to the actual air-fuel ratio. This sensor voltage is
used to provide the ECM with feedback so that it can control the air-fuel ratio. The ECM determines the
deviation from the stoichiometric air-fuel ratio level, and regulates the fuel injection time. If the A/F sensor
malfunctions, the ECM is unable to control the air-fuel ratio accurately.
The A/F sensor is of the planar type and is integrated with the heater, which heats the solid electrolyte
(zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust
gas temperature is low), a current flows into the heater to heat the sensor, in order to facilitate accurate
air-fuel ratio detection. In addition, the sensor and heater portions are narrower than the conventional
type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, therefore
the sensor activation is accelerated.
In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen
oxide (NOx) components in the exhaust gas, a TWC is used. For the most efficient use of the TWC, the
air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.

Rear O2 Sensor:

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen
oxide (NOx) components in the exhaust gas, a TWC is used. For the most efficient use of the TWC, the
air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel level. For
the purpose of helping the ECM to deliver accurate air-fuel ratio control, a Heated Oxygen (HO2) sensor
is used.
The HO2 sensor is located behind the TWC, and detects the oxygen concentration in the exhaust gas.
Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the
oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low).
When the air-fuel ratio becomes lean, the oxygen concentration in the exhaust gas is rich. The HO2
sensor informs the ECM that the post-TWC air-fuel ratio is lean (low voltage, i.e. less than 0.45 V).
Conversely, when the air-fuel ratio is richer than the stoichiometric air-fuel level, the oxygen concentration
in the exhaust gas becomes lean. The HO2 sensor informs the ECM that the post-TWC air-fuel ratio is
rich (high voltage, i.e. more than 0.45 V). The HO2 sensor has the property of changing its output voltage
drastically when the air-fuel ratio is close to the stoichiometric level.
The ECM uses the supplementary information from the HO2 sensor to determine whether the air-fuel ratio
after the TWC is rich or lean, and adjusts the fuel injection time accordingly. Thus, if the HO2 sensor is
working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the
primary air-fuel ratio control.

Information on the Active AF Ratio control (ECU's automatic check of catalytic converter function by forcing rich/lean/rich/lean ratios and verifying O2 sensor output):
http:/www.etimago.com/yaris/repairma...%20Control.pdf - page 126 onward, and page 187 onward

About the short term and long term fuel trims:

The fuel trim is related to the feedback compensation value, not to the basic injection time. The fuel trim
consists of both the short-term and the long-term fuel trims.
The short-term fuel trim is fuel compensation that is used to constantly maintain the air-fuel ratio at
stoichiometric levels. The signal from the Air-Fuel Ratio (A/F) sensor indicates whether the air-fuel ratio is
rich or lean compared to the stoichiometric ratio. This triggers a reduction in the fuel injection volume if the
air-fuel ratio is rich and an increase in the fuel injection volume if it is lean.
Factors such as individual engine differences, wear over time and changes in operating environment
cause short-term fuel trim to vary from the central value. The long-term fuel trim, which controls overall
fuel compensation, compensates for long-term deviations in the fuel trim from the central value caused by
the short-term fuel trim compensation.
If both the short-term and long-term fuel trims are lean or rich beyond predetermined values, it is
interpreted as a malfunction, and the ECM illuminates the MIL and sets a DTC.
When the total of the short-term and long-term fuel trim values is within 20 % (and the engine coolant
temperature is more than 75°C [167°F]), the system is functioning normally.

It's a lot to take in, but these are the basic components that makes the ECU too smart for our own good

It would stand to reason, thus, that successfully running a piggyback would require tweaking the signals not only from the MAF/IAT, but also from the A/F and O2 sensor, so that they report values within the nominal range no matter what. Anybody know of a piggyback that can actually do that? I think the Greddy e-manage Ultimate has some user-programmable inputs and outputs, this could be a contender.

There are O2 sensor simulators in the market that have this sort of functionality, but I do not think they can handle the AF active control check?

Further things to look into:
*How the Blitz fuel controller hooks up, what signals does it affect. This seems to be the only working solution at the moment, in theory anyway.
Can someone email me the installation instructions PDF?

*Compare the functionality of various piggybacks available on the market.

[eTiMaGo]

hey that's a great idea!

[Loren]

What if you went and got sneaky:

The whole system is trying to maintain the AFR at stoich (or probably even leaner in cruise). It gets that info from the O2 sensor(s).

A person who understood how those sensors work could build a circuit to modify their output so that instead of giving the stoich reading at 14.7, it gave a stoich reading at 13.5 or 13.0 or 12.5. The ECU will see 14.7 in that condition and be happy.

A person who's not quite so savvy, but has a little money could just get a commonly available wideband O2 sensor kit, such as the Innovate LC-1, which has programmable outputs. You can have it output whatever voltage range you want, so you could tweak it to lie to the ECU in whatever way you want.

Something to consider, anyhow. Seems like an easy way to get the car to run richer across the board. It won't retard the timing for you, but it will address fueling.

[ChinoCharles]

http://perfectpower.com/products/smt8.asp

AFAIK they should have the pinout for the Yaris on file. Nobody has contacted them yet?

[eTiMaGo]

sounds like that could work too, but what really worries me is the self-test check the ECU does (very rich for a second, then very lean, and see how the sensor reacts. If it does not react, CEL)

though looking back at the manual's explanation, The HO2
sensor informs the ECM that the post-TWC air-fuel ratio is lean (low voltage, i.e. less than 0.45 V). That sounds like reducing the voltage of the sensor's output should be enough to trick the ECU into thinking the system is lean, thus enriching the mixture? Problem is, no way to tune that...

[Loren]

Originally Posted by eTiMaGo

sounds like that could work too, but what really worries me is the self-test check the ECU does (very rich for a second, then very lean, and see how the sensor reacts. If it does not react, CEL)

though looking back at the manual's explanation, The HO2
sensor informs the ECM that the post-TWC air-fuel ratio is lean (low voltage, i.e. less than 0.45 V). That sounds like reducing the voltage of the sensor's output should be enough to trick the ECU into thinking the system is lean, thus enriching the mixture? Problem is, no way to tune that...

I'm not talking about completely faking the O2 signal and locking it down at a fixed value. It would still respond, it would just be "off" a bit, and the ECU would have no way of knowing that.

A system like the LC-1 is VERY tunable. It works like this:
Say the default narrowband O2 sensor output is .45 - 1.5 volts. (not sure if that's right or not, it's something like that) The center of that range represents exactly 14.7.

The LC-1 has not one, but TWO programmable outputs. You could wire one of them to a gauge that would tell you the ACTUAL AFR. The other one you program as a sort of "hybrid wideband" using the standard narrowband voltage range, but centered on something richer than 14.7.

The ECU sees what it expects to see (even though it's not quite the truth), the signal responds to the ECU's commands, and everybody's happy.

Now that I think about it, some additional circuitry may be required to shift the voltage range, but it should be doable. Probably way easier than hacking the ECU.

Tip: The Miata is a far, far more popular car among racers and tuners, and the factory ECU has never been hacked. The closest anyone has ever come is to overclock it with a faster crystal, which has the effect of raising the rev limit and leaning the mixture. I think asking for or waiting for a hack of the Toyota ECU is unrealistic.

[eTiMaGo]

Right, I see what you mean, that could most certainly work too, gonna look more into that

And that's a very sobering fact about the Miata ECU, I would never have guessed!

[Nexus1155]

http://www.allproducts.com/manufactu...911154234.html

probably can score that for pretty cheap if you contact them. I was introduced to the Wideband output signals from a friend a while ago, he said Zeitronix also has them on their kit just to offer an alternative to the LC1.

The SMT8 should work as well as long as it has the programmable outputs as well, this piggyback was also recommended to me by the same person who told me the AFR Gauge trick. The SMT6 that they discountinued can be found for around $150-$200
In theory it should honestly work if the ecu doesn't freak

[eTiMaGo]

Originally Posted by PK198105

i can almost guarantee a CEL, since the ECU is programmed with safety margins and thresholds.

Yes, but, what I mean is, if you want to run a richer than stoich ratio without the ECU freaking out, you need to fool it into receiving "normal" signals.

Say that at stoich (14.7:1 AFR) the O2 sensor has a voltage of 2.5V Your target AFR is, let's say, 12:1, which would (I'm guessing) correspond to a voltage of 3.5V from the sensor. The trick would thus be to change this 3.5V to 2.5V so the ECU thinks the catalytic system is working just fine and there's no problem.

Originally Posted by Nexus1155

http://www.allproducts.com/manufactu...911154234.html

probably can score that for pretty cheap if you contact them. I was introduced to the Wideband output signals from a friend a while ago, he said Zeitronix also has them on their kit just to offer an alternative to the LC1.

The SMT8 should work as well as long as it has the programmable outputs as well, this piggyback was also recommended to me by the same person who told me the AFR Gauge trick. The SMT6 that they discountinued can be found for around $150-$200
In theory it should honestly work if the ecu doesn't freak

I guess the question now becomes, who's gonna be willing to experiment with some of these?